漂浮式风力机Spar平台摇荡运动混沌特征分析

Study of the Collision of a Mono-pile Type Offshore Wind Turbine with a Ship Based on the Compound Foundation Reaction Force Method

漂浮式风力机Spar平台在非规则环境载荷作用下运动具有很强的随机性和非线性。为分析平台动态响应中的非线性动力学特征,首先建立基于OC3Spar平台的NREL 5 MW风力机整机模型,采用水动力软件AQWA求解Spar平台的运动特性,进一步采用功率谱法、相空间重构以及最大Lyapunov指数法定性、定量两方面判断Spar平台在波、浪、流载荷作用下摇荡运动时间序列的混沌特征。研究表明：Spar平台在低频时运动幅值较大;平台在多重载荷作用下在平衡位置处摇荡运动;平台在纵荡、垂荡及纵摇方向上的运动时间序列具有混沌特征,且3个方向短期可预测时间最大为6.14 s。混沌理论可作为漂浮式风力机平台非线性运动分析的一种新方法。

The Spar platform of a floating type wind turbine has a very strong stochasticity and nonlineari- ty under the action of irregular environmental loads. To analyze the nonlinear dynamic characteristics of the platform in the dynamic responses, a whole machine model of a 5 MW NREL wind turbine was established based on the OC3Spar platform and the hydrodynamic software AQWA was adopted to solve solutions to the movement characteristics of the Spar platform. Furthermore, the power spectrum method, phase space reconstruction and maximal Lyapunov index method were used to qualitatively and quantitatively judge the chaotic characteristics of the swaying movement time sequence under the action of wave and current-caused loads. It has been found that the movement amplitude of the Spar platform will be relatively big at low frequencies and the platform will be in a swaying movement at its equilibrium position under the action of multiple heavy loads. The movement time sequence will assume the chaotic characteristics in the swing, heaving and pitching direction and the time duration predicted in the short term in the said three directions will be maximally 6.14 s. The chaos theory can serve as a new method for analyzing the nonlinear movement of the platform for the floating type wind turbine.